Thousands of young people marched through the streets of Glasgow yesterday to protest a lack of climate action with a clear message to negotiators at the COP26 summit: "If not now, when?" 

Inside the COP26 conference venue in the Scottish city, civil society leaders took over discussions at the end of a week of government speeches and pledges that included promises to phase out coal, slash emissions of the potent greenhouse gas methane and reduce deforestation.

"We must not declare victory here," said former US Vice President Al Gore, who shared the 2007 Nobel Peace Prize for his work informing the world about climate change. "We know that we have made progress, but we are far from the goals that we need to reach."

Campaigners and pressure groups have been underwhelmed by the commitments made so far, many of which are voluntary, exclude the biggest polluters, or set deadlines decades away.

Swedish teenage activist Greta Thunberg said that pledges from some nations made during COP26 to accelerate their emissions cuts amounted to little more than "a two-week long celebration of business as usual and 'blah, blah, blah'."

"It is not a secret that COP26 is a failure," she told the thousands of people gathered at the protest.

"This is no longer a climate conference. This is now a global greenwashing festival."

Campaigners say they expect up to 50,000 demonstrators in the Scottish city today as part of a global round of climate protests.

Onlookers to yesterday's march lined the streets and hung out of windows to watch the stream of protestors, who held banners reading "No Planet B" and "Climate Action Now".

Sixteen-year-old protester Hannah McInnes called climate change "the most universally devastating problem in the world", adding: "It's our lives and our futures that are on the line."

The talks aim to secure enough national promises to cut greenhouse gas emissions - mainly from fossil fuels - to keep the rise in the average global temperature to 1.5 degrees Celsius.

Countries came into COP26 with national climate plans that, when brought together, put Earth on course to warm 2.7C this century, according to the UN.

With just 1.1C of warming so far, communities across the world are already facing ever more intense fire and drought, displacement and economic ruin wrought by the Earth's heating climate.

To that end, the United Nations wants countries to halve their emissions from 1990 levels by 2030, on their way to net-zero emissions by 2050. That would mean the world would release no more climate-warming gases than the amount it is simultaneously recapturing from the atmosphere.

The summit on Thursday saw 23 additional countries pledge to try to phase out coal - albeit over the next three decades, and without the world's biggest consumer, China.

A pledge to reduce deforestation brought a hasty about-turn from Indonesia, home to vast and endangered tropical forests.

But a plan to curb emissions of methane by 30% did appear to strike a blow against greenhouse gases that should produce rapid results.

And city mayors have been working out what they can do to advance climate action more quickly and nimbly than governments.

The Glasgow talks also have showcased a jumble of financial pledges, buoying hopes that national commitments to bring down emissions can actually be implemented.

But time was running short. "It is not possible for a large number of unresolved issues to continue into week 2," COP26 President Alok Sharma said in a note to negotiators published by the United Nations.

Efforts to set a global pricing framework for carbon, as a way to make polluters pay fairly for their emissions and ideally finance efforts to offset them, are likely to continue to the very end of the two-week conference.

New Zealand Prime Minister Jacinda Ardern yesterday warned that the Glasgow climate summit was "make or break" in the fight to curb global warming, saying the world is now paying the price for decades of procrastination.

She called for the UN-brokered talks to result in immediate and meaningful action, adding "we're definitely at a point now where it's moved beyond targets".

However, US climate envoy John Kerry said that it was still possible to reach a deal at the summit settling the final details of the rulebook for how to interpret the 2015 Paris Agreement.

He said the United States was in favour of "the most frequent possible" assessments of whether countries were meeting their goals to reduce emissions.